WO 91/02878 and WO 93/15296 relate to a vacuum-insulated glass comprising two adjoining glass panes enclosing an evacuated space. The glass panes are spaced apart from one another by spacer assemblies and joined by means of an edge seal around the circumference. The vacuum between the glass panes is generated via opening in one of the glass panes. The known vacuum-insulated glasses have not been able to establish themselves on the market. The vacuum-insulated glasses currently available on the market have only been able to achieve inadequate thermal insulation values (U values) of 1.0 W/(m2K) or less, but these values are easily achieved with standard insulating glasses. Indeed, laboratory-scale research has shown that U values of up to approximately 0.4 W/(m2K) are achieved, but these results were practically limited to small-scale laboratory patterns. The transfer of the laboratory experiments to larger formats of at least 0.8 m2 and more were unsuccessful thus far. This is mainly due to the fact that a host of unresolved practice-related problems concerning the functionality and usability are associated with the known vacuum-insulated glasses. For example, the practical use of the known vacuum-insulated glasses very often results in impairment or damage in the form of breakage of glass, leakiness or loss of vacuum etc. which in many cases can result in the complete uselessness or complete failure of the component. This mainly affects areas at the interlocked edges and especially the comers. It was determined that these shortcomings only become manifest with larger geometrical dimensions of at least approximately 0.4 m2 and especially larger, while said occurrences have not been observed in the small laboratory patterns in the format of typically at most 500 mm×500 mm (up to areas of at most 0.25 m2).
Some disadvantages and other technology-related problems associated with the known vacuum-insulated glasses are described in more detail below. In the practical application, vacuum-insulated glasses are required to withstand varying, potentially extreme exterior conditions without any loss of function and damage. Such changing conditions are associated e.g. with fluctuating seasonal weather conditions. For example, exterior temperatures in winter can definitely reach values of −20° C. to −25° C. and lower, while temperatures inside the building typically hover around +20° C. Consequently, a temperature difference between the interior and exterior pane of 40K to 50K and greater is common. These high temperature differences also occur in vacuum-insulated glasses in cooling facilities. Moreover, the vacuum-insulated glasses are exposed to high heat in the summer time. Aside from the high exterior air temperatures of 30° C. to 40° C., high sun irradiation with values typically ranging between at least 800 W/m2 to 1.200 W/m2 also occur. As well, it is possible that the inward facing glasses are additionally exposed to convective cooling for example due to air conditioning and/or high humidity (for example in the bath or sanitation facilities). However, the outward facing glasses can equally be prone to additional signs of exposure, for example as a result of wind, rain, snow, ice rain etc. To preserve the full usability, vacuum-insulated glasses are required to meet these complex requirements in their entirety. Practice has shown that the traditional vacuum-insulated glasses thus far failed to achieve this or only achieve it to a very limited degree.
The mentioned temperature differences cause deflections between the exterior and interior panes of vacuum-insulated glasses—similar to the bimetal effect—which are largely compensated by the vacuum edge seal. The associated excessive shearing forces in the area of the vacuum edge seal and/or the elevated tensile stress on the glass surface damage or destroy the entire glazing element. The resulting forces can reach values of up to 20 MPa and more. This is especially disadvantageous in cases in which the insulation (U value in the centre of the component) of the vacuum-insulated glasses is typically smaller or equal to 0.8 W/(m2K), because the heat exchange and as a result ultimately the temperature equalisation between the glass panes is almost completely inhibited. This problem has not yet been resolved for highly insulating vacuum-insulated glasses with sizes of 0.4 m2 and more.
Another disadvantage is that the spacer assemblies between the individual glass panes represent cold bridges and undesirable locally confined condensation may be observed preferably at the positions of the spacer assemblies as a result. This effect is all the more pronounced the lower the temperature on one side of the glazing is and the greater the resulting temperature difference between the two glass panes is. This is particularly bothersome in connection with exterior glazing during the cold season or in connection with vacuum-insulated glasses in refrigerating sets. The known vacuum-insulated glasses are not suitable to adequately minimize or prevent this undesirable effect.
An additional disadvantage of the traditional vacuum-insulated glazing is that it can not be produced fully serviceable in any arbitrary geometrical shapes, outlines and sizes. This also applies in particular to vacuum-insulated glasses comprising a bent, curved or other shape that deviates from a planarity.
An additional disadvantage is that the traditional vacuum-insulated glasses are significantly more expensive compared to conventional insulated glasses. To this day it has been impossible to significantly reduce the costs by means of improved process technology.
It could therefore be helpful to provide an improved insulating glazing element with which the disadvantages of traditional vacuum-insulated glasses can be overcome. Moreover, it could be helpful to provide an improved component comprising said glazing element and cost-efficient methods for the manufacture of the glazing element and the component.